Friday, October 4, 2013

Species that don’t get enough publicity #1- Diadectes sideropelicus

Ah, Dimetrodon. The only nonmammalian synapsid (basically the ancestors of modern mammals) ever
to become an honorary dinosaur.It’s ubiquitous
in art, toys, and museums. It’s better known than hundreds of dinosaurs, let
alone members of its own group. Sometimes Dimetrodon lies right between lobe-finned fish
and Stegosaurus in a march of history. That sail overshadows the Triassic,
Permian, and Carboniferous periods. Sometimes other Permian animals show up in
popular culture-Eryops, looking like nothing else but a crocodile frog, or
Edaphosaurus, which is just the plant eating version of Dimetrodon (And so, not
as popular), but it’s all Dimetrodon.

That’s why I’m not going to talk about Dimetrodon anymore.Instead, I’m going to talk about an animal I
find actually more interesting.It was
probably harmless (on the other hand, even Dimetrodon probably wouldn’t be any
more dangerous than an alligator, Nile Monitor or Tasmanian devil), about
the size of a large dog, and people have struggled for years whether it’s a
reptile of an amphibian. The American, Field, and Harvard museums all have one
right next to their Eryops, Dimetrodon, etc, but it’s probably overlooked by
most visitors.

-Illustration by Robert Bakker

This animal is Diadectes. This animal has never been on
film, or shown in a documentary. This is despite, or more likely because of,
the fact that this is the first herbivorous tetrapod.People like their dinosaurs, not what
scuttled around the northern hemisphere during the Permian period. Diadectes is
very much the opposite of the dinosaur posterchild Tyrannosaurus. It’s low
slung, stocky, buck-toothed, sluggish, plant-munching,and only the size of a Newfoundland (minus
the tail). It didn’t have any spikes or horns or armor for defense, or frills
or plates or fins for display. It went extinct fairly unspectacularly-the
Permian became drier, and it was supplanted by pelycosaurs like
Cotylorhynchus.I only found out about this genus in a book featuring
(surprise!) Dimetrodon, where it acted as a one-page dinner for the synapsid
protagonist.

So why should we know more about this animal? Ecology,
taxonomy, and physiology.On land, the
only plant-eaters were species of insects for millions of years. They in turn
were preyed upon by insectivorous arthropods, amphibians and reptiles. Amphibians
and reptiles solely ate other animals-whether fish, tetrapod, or invertebrate.
The two species of Diadectes (D. sideropelicus and D. tenuitectus) and its relatives in their own
order, Diadectamorpha, were the earliest tetrapod to eat plants. The earliest genus
found is Desmatodon, a small animal from the late Carboniferous, but Diadectes
itself could grow up to 10 feet long and probably weighed as much as a human
being.

Mount of Diadectes at Field Museum

Instead of straight piscivorous or insectivorous teeth like
the Pelycosaurs, or the curved teeth of predators like Dimetrodon or
Sphenacodon, it had large, wide teeth for chopping plants. It even had a
primitive chewing apparatus-the wide chopping front teeth, broad crushing cheek
teeth, and one of the first secondary palates (the skull structure separating the
nose from the mouth, allowing animals to breathe while eating) in nature. Diadectes was soon followed by the equal-sized
Edaphosaurus (they shared the Early Permian as prey species for Dimetrodon),
the gigantic Cotylorhynchids (bucktoothed, tiny-headed blimp shaped pelycosaurs
described aptly by Dr. Tom Holtz as “derpy”), and then all the synapsids,
diapsids, dinosaurs, and mammals that developed herbivory to take advantage of
Earth’s lush plant life.Diadectes was
the ur-cow, if you will.

The weirdest part isn’t just the size and diet; it’s their
classification. They’ve been assigned to a group called reptilomorpha. These
are amniotes (animals laying hard shelled eggs) that are neither amphibians nor
true reptiles.The Reptilomorphs (called
Anthracosaurs by some) also include the small aquatic Lepospondyls, the Seymouriamorphs which spent their juvenile lives as
amphibians and adult lives as reptiles, the crocodile like Chroniosuchids, the
aquatic predator Embolomeres and the very small, early Gephyrostegids . All
these animals have deep skulls, horizontally placed eyes, deep torsos with
strong legs for crawling around, and a heavy build overall.

I recall reading
many books, some of which placed Diadectes with the amphibians; others placed
it as a reptile. Truth is, we’re still not sure. It’s one of the many, many
problematic animals when it comes to organizing reptiles and amphibians. Both
groups are astoundingly diverse today, and are even more so across geological
history.

I guess I just have
a fondness for this taxon. Maybe because you can almost spell my name with
Diadectes. Maybe it’s my rooting for the underdog and affection for herbivores.
Maybe I just like the big dumpy bucktoothed critter. If I were a Permian
animal, I’d probably be one. Lumbering around, not a thought in my big dumpy
head, munching on ferns and fermenting them in my gut, only having to worry
about hungry Dimetrodons. It’s not much,
but it’s a nice, slow life, like any other in the early Permian.

So anyway,Hollywood, give this guy a break. Museums,
keep him on display. Toy companies, here’s a new fresh face. Authors,think about the crap you’re writing and how
this genus could perk up the place. And remember, shop Diadectes where you work
or play.

For a related
opinion, here’s palaeontologist David Button on this loveable critter http://evopalaeo.blogspot.com/2013/03/diadectes-worlds-first-badass.html

2 comments:

Paleontology offers itself as a tool and scope through which you can view the world; it reminds you that humans are just one of the many million species that have roamed on this Earth. Paleontology is a branch of science that aims to paint a picture of the past, a place that we no longer have direct access to. However, paleontology acts as the bridge that connects us and gives us the ability to travel through time.

About Me

Hi everyone! You may know me already, but 99% of you won't. I've decided to make a blog for myself. I'm a anthropology student who has returned to his original passion for palaeontology. Ever since I was little, I've been fascinated with the weird and wonderful animals that have inhabited our planet and I've made this blog to keep this in my mind and hopefully in yours. Most people blog about their interests, and while I've got a range of interests-see history and anthropology above, not to mention zoology, astronomy, art, cooking, science fiction and fantasy films and literature, and a myriad of others, the one I want to do for a living is the study of Earth's ancient past.

On this blog I'll review papers, talk about fossils, museums, and taxa, review art, film, literature, and our culture's view of paleontology, and share memories and insights. I've been inspired by the far better blogs of professional palaeontologists, and I'll share them as time goes on. I'm also open to requests and questions of opinions, the latest palaeo news, and discussions with other fans informal and professional.

I think this is going to have fun, and I'm hoping my readers will have just as much fun.

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